Method and apparatus for the manufacture of paper



July 17, 1962 J, BERLYN 3,044,925

METHOD AND APPARATUS FOR THE MANUFACTURE OF PAPER Filed Nov. 20, 1958 2Sheets-Sheet 1 M LIFE/um IrranMs-"X M. J. BERLYN July 17, 1962 METHODAND APPARATUS FOR THE MANUFACTURE OF PAPER 2 Sheets-Sheet 2 Filed Nov.20, 1958 1 /NVEN7'0R M I BERL y/v a A 3,044,925 Patented July 17, 19623,044,925 METHOD AND APPARATUS FOR THE MANUFACTURE or PAPER Martin J.Berlyn, Montreal, Quebec, Canada,,assignor to This invention relates toimprovements in the manufacture of paper and, while applicable to themanufacture of paper at conventional speeds, is especially useful forthe manufacture of paper at speeds greatly in excess of conventionalspeeds. More particularly, the invention'is concerned with that phase ofpaper-making which consists in forming an aqueous suspension ofpaper-making fibres into a wet web or sheet.

In the manufacture of paper at high speed in a continuous sheet,according to contemporary practice, a suspension of fibres in water,known in the industry as the stock, is flowed onto the substantiallyhorizontal upper run of a moving endless belt of wire cloth, known inthe industry as the wire.

Water drains from the stock through the wire as the wire carries it fromthe region of the breast roll towards the couch roll. As it is flowedonto the wire, the stock usually has a consistency of (parts by weight)one part of fibre to two hundred of water; such would be described as0.5 stock.

Supporting the upper run of the wire are a number of rolls, known astable rolls whose function is to accelerate the drainage of water fromthe stock through the wire. A given element of stock, deposited on themoving wire near the breast roll, loses water progressively as the wirepasses over the table rolls in its travel towards the couch roll; theconsistency of this element of stock therefore increases progressivelyas it travels away from the breast roll.

At a point in its ride on the wire where the consistency of this elementof stock has risen to about 2.5%, or (parts by weight) one part of fibreto forty of water, table rolls are no longer effective in acceleratingthe drainage of water from it.

Just beyond the last table roll, in the direction of travel of the wire,a series of suction boxes, sometimes known as fiat boxes, is employed toaccelerate drainage of water from the (now) high-consistency stock onthe wire.

The wire slides over the upper faces of the flat boxes;

these upper faces are provided with openings which are in communicationwith vacuum pumps.

Before the wet web of fib're is removed from the wire, the wire wrapsonto a perforated suction couch roll which is provided with an internalsuction box connected with a vacuum pump.

The web, as it finally leaves the wire, is about 20% dry, which is tosay, that it consists of (parts by weight) one part of fibre to four ofwater.

A disadvantage of this method of forming a web is the enormous volume ofmaterial which must be handled because the consistency of the stock, asflowed onto the wire, must be kept in the neighbourhood of 0.5% in orderto achieve acceptably uniform dispersion of the fibres in the water.Unless this uniformity of dispersion is achieved, the formation of thesheet is unacceptable. This is due to the phenomenon of floccing of thefibres, which insist on congregating into bundles unless dispersed in adilute suspension.

Another disadvantage of this method is that the cost of Fourdrinierwires is high while their life-expectancy is low; also the time taken tochange wires represents loss of production and, in effect, reduces theefiiciency of the machine.

With further reference to the phenomenon of floccing of the fibres inhigh-consistency stock, when the consistency is above 2% floccing is somarked that the appearance of a free surface of such stock isreminiscent of a pebbled surface. The size of the individual bundles offibres varies only slightly; furthermore, the average size of thebundles does not change significantly over a 2% to 12% range ofconsistencies.

A major contributory factor to design stagnation in the field ofweb-forming devices has been the difliculty of achieving thedefiocculation of high-consistency stock.

The conventional low-consistency stock, however, is not without itsproblems also; and is, in one respect, a victim of its own diluteness.It suifers from a tendency to reflocculation in the interval betweenadmission to the headbox and discharge from the slice because, in thepresence of much Water, the individual fibres are free to swim 'to eachother and satisfy their disposition to congregate into bundles.

High-consistency stock, on the other hand, having a tenth, say, of theamount of water, does not provide individual fibres with the freedom ofmovement that they require for refiocculation. For this reason 5% stock,once it has been deflocculated, is more stable than defluocculated 0.5%stock.

This invention covers a method of deflocculating highconsistency stockand a method of forming a web without the use of a wire; it is moreparticularly dedicated to the manufacture of paper at speeds in theorder of lOOqfeet per second, and higher, though not excluded from useat lower and more conventional speeds.

In the method of forming a web according to this invention theconsistency of stock fed to the web-forming device is about ten timesthat employed in contemporary paper-making machinery, or in the order of5% fibre by weight.

Deflocculation of the fibres is effected by dissolving a gas underpressure into the stock and forcing this gas-impregnated stock throughan orifice at high velocity into a diffuser or expansion chamber.

There is a substantial and rapid pressure drop in the stock as it passesfrom the upstream side to the downstream side of the orifice. As aconsequence of this pressure drop, dissolved gas comes out of solutionin the form of bubbles which, growing between adjacent fibres, forcethem apart and break up the bundles or flocs.

The sudden increase of volume which takes place as a result of theformation of gas bubbles within the stock creates turbulence.

Simultaneous forced turbulence and separation of adjacent fibres resultsin deflocculation of the stock. I

The expansion chamber is provided with a slice outlet proportioned togive the desired stock exit velocity.

The stream of defiocculated stock issuing from the slice is received bythe web-forming device which compactsit and forms it into a web bypassing it through a series of pairs of rolls.

The first stages of compacting consists chiefly of bursting the bubblesin the stock; thelast stage of com- Another object is to reduce thephysical size of the equipment used in the manufacture of paper.

Another object is to eliminate the use of costly, shortlife, expandablecomponents from web-forming devices used in the manufacture of paper, asfor example Fourdrinier wires.

Another object is to provide paper-manufacturing means which do notdemand periodic down-time for renewal of expendable components such asFourdrinier wires.

FIG. 1 is a vertical schematic elevation in a plane parallel with theplane of the web.

FIG. 2 is a vertical schematic elevation in a plane normal to the planeof the web.

FIG. 3 is a section, on an enlarged scale, in a plane normal to theplane of the web, through the deflocculator device.

FIG. 4 is an enlarged partial schematic vertical section, in a planenormal to the plane of the web, showing the means for catching waterremoved from the web.

FIG. 5 is an enlarged partial schematic vertical elevation, in a planenormal to the plane of the web, indicating the arrangement of drivinggears for the rolls shown in FIGS. 1, 2, and 4.

FIG. 6 is a view, similar to FIG. 3, but showing a modified design ofdeflocculator device.

With reference to FIGS 1, 2 and 3, high-consistency stock from a stocktank 1 passes through stock feed duct 2 to stock pump 3.

A source of compressed gas 4 is ducted to a gas flow control device 5from which gas duct 6 leads gas to the stock pump discharge duct 7.

Stock pump discharge duct 7 is connected to the inlet end 8 of plenumchamber 9.

Plenum chamber 9, at its discharge end 10 feeds deflocculator 11.

Deflocculator 11 is shown in section, to an enlarged scale, in FIG. 3from which it will be seen that stock flows into it through acontracting passage 12 to a constriction 13 which opens into a diffuseror expansion chamber 14.

From diffuser 14 the stock passes into an accelerating chamber 15 whichis provided with a slice outlet 16.

It is to be noted that the stock path throughout the length of thedeflocculator 11, as shown in FIG. 3, is the full width of the web to beformed.

It is also to be noted that the gas from the source of compressed gas 4is of a nature having the characteristic of solubility in water as, forexample, air.

From the slice outlet 16 the stock issues in a stream 17 which passesbetween rolls 18.

The diameter of these rolls is such that, at the linear speed ofoperation of the web-former or given angular velocity of the roll, thecentrifugal efiect at the periphery of the rolls is of the order of 10times gravity.

This diameter is chosen in order to prevent adhesion of fibres to theroll surfaces and to provide that the stock leaves the roll nip in acompact stream instead of a diffused spray.

Due to the action of rolls 18 in bursting gas bubbles, the stream ofstock is reduced in thickness in its pass through the nip.

Passing from rolls 18 in a somewhat compacted stream, the stock passesthrough the nips of pairs of rolls 19, 20, 21 and 22 in succession andis further compacted in its passage through each pass.

Rolls 19 are provided with circumferential lands 23 somewhat wider thanthe grooves 24 between the lands 23. The lands 23 on each of the tworolls 19 are mutually registered in planes normal to the roll axes.Stock passing through the nip of rolls 19 is therefore wrung inlongitudinal stripes which coincide with the registered pairs ofperipheral lands 23 on the roll surfaces.

Water removed from the stock, where it is squeezed between pairs of rolllands 23, escapes into the spaces formed by registered pairs of rollgrooves 24 whence it 4 is centrifuged off rolls 19 and deflected bystrippers 25 (FIG. 4) into troughs 26.

Rolls 20 are provided with circumferential lands 27 of the same width asthe lands 23 on rolls 19 and therefore somewhat wider than the grooves28 between the lands 27 on rolls 2t Lands 27 on each of the two rolls 20are mutually registered in planes normal to the roll axes. Stock passingthrough the nip of rolls 20 is therefore wrung in longitudinal lands 27.

Water removed from the stock, where it is squeezed between pairs of rolllands 27 into the spaces formed by registered pairs of roll grooves 28whence it is centrifuged off rolls 20 and deflected by strippers 25 intotroughs 26.

It is to be noted that the longitudinal stripes wrung by the lands 27 ofrolls 20 are in staggered relationship to the longitudinal stripes wrungby the lands 23 of rolls 19 and, since the lands 23 and 27 are widerthan the grooves 24 and 28, the wrung longitudinal stripes due to lands27 on rolls 20 overlap the wrung longitudinal stripes due to the lands23 on rolls 19.

Rolls 21 are provided with uniformly spaced longitudinal lands 29parallel with the roll axes; lands 29 are somewhat wider than grooves 30between lands 29. Rolls 21 are mutually phased so that lands 29 registerwith lands 29 and grooves 30 with grooves 30, at the nip between the tworolls 21.

It will be seen that, in passing through the nip of rolls 21, the stock,is wrung in transverse stripes.

Water removed from the stock, where it is squeezed between pairs of rolllands 29 escapes into the spaces formed by registered pairs of rollgrooves 30 whence it is centrifuged off rolls 21 and deflected bystrippers 25 into troughs 26.

Rolls 22 are provided with uniformly spaced longitudinal lands 31parallel with the roll axes; lands 31 are somewhat wider than grooves 32between lands 31.

Rolls 22 are mutually phased so that lands 31 register with lands 31,and grooves 32 with grooves 32, at the nip between the two rolls 22.

It will be seen that, in passing through the nip of rolls 22 the stockis wrung in transverse stripes.

Water removed from the stock, where it is squeezed between pairs of rolllanrls 31, escapes into the spaces formed by the registered pairs ofroll grooves 32 whence it is centrifuged off rolls 22 and deflected bystrippers 25 into troughs 26.

The pair of rolls 22 is so phased with relation to the pair of rolls 21that the transverse stripes wrung by rolls 22 are in staggered relationto the transverse stripes wrung by rolls 21. Since lands 29 are widerthan grooves 30 and lands 31 are wider than grooves 32, the transversestripes wrung by rolls 22 overlap the transverse stripes wrung by rolls21.

It will therefore be seen that the entire stream of stock,

1 in passing successively through five roll nips, has been subjectedfirst to preliminary compacting, then to wringing in overlappinglongitudinal stripes and, finally, to wringing in overlapping transversestripes.

Pairs of rolls 18, 19, 20, 21 and 22 (see FIGS. 1 and 5) are driven bypairs of synchronizing gears 33, 34, 35, 36, and 37 respectively.

Synchronizing gears 33 and 34 are phased by pinion 38; synchronizinggears 34 and 35 are phased by pinion 39; synchronizing gears 35 and 36are phased by pinion 40 and synchronizing gears 36 and 37 are phased bypinion 41.

After leaving the nip of rolls 22 the web is passed through a press, orpresses, 42 of the type disclosed in our US. co-pending applicationSerial No. 699,255, filed November 27, 1957, now Patent No. 2,885,954.

In the modification shown in FIG. 6 the inside configuration of thedeflocculator 11 is such as to give a more sudden expansion as comparedwith the configuration shown in FIG. 3. In this connection, it will benoted that the diffuser section 14 shown in FIG. 6 has, throughout itslength, a substantially uniform inside diameter considerably greaterthan that of the communicating constriction 13. Y

It may also be noted, at this point, that the invention is notrestricted to the use of the particular design of web-forming rollsshown in the present dravw'ngs. On

' the contrary, it is feasible to provide the rolls 19, 20, 21

and 22 or, in fact, all of the rolls with either circumferential groovesand lands or helical grooves and lands.

When helical grooves and lands are employed, the helical grooves andlands on each of a pair of cooperating rolls may be of the same hand ormay be of opposite hands; in the former case, the wringing would be in adiamond-shaped pattern while, in the latter case, the wringing would bein diagonal stripes.

It may be also pointed out that the term high consistency paper stock,as used in the preceding description and in the appended claims, isintended to designate a stock having a consistency within the range offrom approximately 2.%'to 12% higher.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A method of forming a high consistency aqueous suspension of fibresin the order of five percent consistency into a sheet which compriseseffecting pressure impregnation of the stock with a water-soluble gas,forcing the gas-impregnated stock through a orifice at high velocityinto an expansion zone in which dissolved gas comes out of solution inthe form of bubbles which serve to deflocculate the stock by forcingadjacent fibres apart and which also breaks up flocs and createsturbulence, delivering the deflocculated stock from the expansion zonein a downwardly flowing stream, and subjecting the downwardly flowingdeflocculated stream of stock to compacting pressure applied thereto atdifferent points along the length of the downward path of travel of saidstream to thereby force water and gas from the downwardly flowing streamof stock and compact the fibrous components of the stream into a sheet.

2. A method of forming a high consistency aqueous suspension of fibresin the order of five percent consistency into a sheet which compriseseffecting pressure impregnation of the stock with a water-soluble gas,forcing the gas-impregnated stock through an orifice at high velocityinto an expansion zone in which dissolved gas comes out of solution inthe form of bubbles which serve to deflocculate the stock by forcingadjacent fibres apart and which also breaks up flocs and createsturbulence, delivering the deflocculated stock fromthe expansion zone ina downwardly flowing stream, and subjecting the downwardly flowingdeflocculated stream of stock to compacting pressure to force water andgas from the downwardly flowing stream of stock and compact the fibrouscomponents of the stream into a sheet.

3. Apparatus for forming a high consistency aqueous suspension of fibresinto a sheet which comprises a defiocculator including an expansion zonehaving a restricted stock inlet orifice, means for first impregnatingthe stock with a water-soluble gas under pressure and then forcing thegas-impregnated stock through said orifice and into said expansion zoneand compacting means through which a stream of deflocoulated stock ispassed from the deflocculator to compact the fibrous components of thestream into a sheet.

4. Apparatus as set forth in claim 3 in which the stock is passed fromthe deflocculator in a downwardly flowing stream and in which thecompacting means comprises a vertical series of pairs of compactingelements arranged so that the downwardly flowing stream of stock passesbetween and is subjected to compacting pressure by the v compactingelements of each pair.

5. Apparatus as set forth in claim 3 in which the stock is passed firomthe deflocculator in a downwardly flowing stream and in which thecompacting means comprises a vertical series of pairs of compactingrolls arranged so that the downwardly flowing stream of stock passesbetween and is compacted by the rolls of each pair.

6. Apparatus as set forth in claim 3 in which the stock is passed fromthe deflocculator in a downwardly flowing stream and in which thecompacting means comprises a vertical series of pairs of compactingrolls arranged so that the downwardly flowing stream of stock passes between and is compacted by the rolls of each pair, said compacting meansbeing further characterized in that the component rolls of at leastcertain of said pairs of rolls are provided with grooves and lands.

7. Apparatus as set forth in claim 3 in which the stock is passed fromthe deflocculator in a downwardly flowing stream and in which thecompacting means comprises a vertical series of pairs of driven rollsarranged so that the downwardly flowing stream of stock passes betweenand is subjected to pressure by the rolls of each pair, said compactingmeans being further characterized in that the diameter at a givenangular velocity of the rolls is such that the centrifugal effect at theperiphery of the rolls is of the order of 10 times gravity.

8. Apparatus for forming a high consistency aqueous suspension of fibresinto a web or sheet which comprises a tank containing the highconsistency stock, a plenum chamber, a pump through which the stock ispumped from the tank to the plenum chamber, a source of watersoluble gasunder pressure, a duct through which gas from said source is introducedinto the stock at the discharge side of the pump, a deflocculator towhich the gas impregnated stock is delivered from the plenum chamber,and compacting means through which a stream of deflocculated stock ispassed from the deflocculator.

9. Apparatus as set forth in claim 8 in which the deflocculator includesan expansion zone in which dissolved gas comes out of solution in theform of bubbles which serve to force adjacent fibres apart to break upflocs and to create turbulence which causes random orientation of thefibres.

10. Apparatus as set forth in claim 8 in which the deflocculatorincludes an expansion zone in communication with the plenum chamber viaa restricted orifice through which stock is delivered from the plenumchamber to the expansion zone, said apparatus being characterized inthat the gas comes out of solution in the expansion zone in the form ofbubbles which serve to deflocculate the stock by forcing adjacent fibresapart and to arrange the fibres in random orientation.

11. Apparatus as set forth in claim 8 in which the deflocculatorincludes an expansion zone, a restricted orifice through which stock isdelivered from the plenum chamber to the expansion zone and anaccelerating zone through which the stream of stock is delivered fromthe expansion zone to the compacting means.

12. Apparatus as set forth in claim 8 in which the stock is passed fromthe deflocculator in a downwardly flowing stream and in which thecompacting means include a plurality of pairs of rolls arranged invertical series so that the downwardly flowing stream of stock passesbetween and is subjected to pressure by the rolls of each pair.

13. Apparatus for forming a high consistency aqueous suspension offibres into a sheet or web, comprising a deflocculator including anexpansion zone having a restricted stock inlet orifice, means forimpregnating the stock with a water-soluble gas under pressure andforcing the gas-impregnated stock said orifice and into said expansionzone and compacting means through which a downwardly flowing stream ofdeflocculated stock is passed from the deflocculator, said compactingmeans including a plurality of pairs of rolls arranged in verticalseries so that the downwardly flowing stream of stock passes between andis subjected to pressure by the rolls of each pair, deflectorspositioned below each pair of rolls and troughs into which watercentrifuged from the rolls is 1,875,075 deflected by the deflectors.2,691,796 2,969,114

References Cited in the file of this patent UNITED STATES PATENTS 5 41821,519,696 Nishina Dec. 16, 1924 356,294 1,659,688 Hinde Feb. 21, 1928748,095

8 Mason Aug. 30, 1932 Emig Oct. 19, 1954 Baxter Jan. 24, 1961 FOREIGNPATENTS Great Britain of 1881 Great Britain Sept. 10, 1931 Great BritainApr. 18, 1956

1. A METHOD OF FORMING A HIGH CONSISTENCY AQUEOUS SUSPENSION OF FIBRESIN THE ORDER OF FIVE PERCENT CONSISTENCY INTO A SHEET WHICH COMPRISESEFFECTING PRESSURE IMPREGNATION OF THE STOCK WITH A WATER-SOLUTION GAS,FORCING THE GAS-IMPREGNATED STOCK THROUGH A ORIFICE AT HIGH VELOCITYINTO AN EXPANSION ZONE IN WHICH DISSOLVED GAS COMES OUT OF SOLUTION INTHE FORM OF BUBBLES WHICH SERVE TO DEFLOCCULATE THE STOCK BY FORCINGADJACENT FIBRES APART AND WHICH ALSO BREAKS UP FLOCS AND CREATESTURBULENCE, DELIVERING THE DEFLOCCULATED STOCK FROM THE EXPANSION ZONEIN A DOWNWARDLY FLOWING STREAM, AND SUBJECTING THE DOWNWARDLY FLOWINGDEFLOCCULATED STREAM OF STOCK TO COMPACTING PRESSURE APPLIED THERETO ATDIFFERENT POINTS ALONG THE LENGTH OF THE DOWNWARD PATH OF TRAVEL OF SAIDSTREAM TO THEREBY FORCE WATER AND GAS FROM THE DOWN-